Task deletion and page navigation reliability fixes

Deleting tasks with many attached files now completes reliably. Previously, deleting a task with a large number of files could fail partway through, leaving the task in an inconsistent state. The deletion now runs to completion every time.
An unexpected error message on certain page transitions is resolved. Some users were occasionally shown an "unexpected response" error when the app redirected them between pages — for example, after a session change or when accessing a page they don't have permission to view. These redirects now work smoothly without showing an error.